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Monday, November 25, 2013

Plastic for Dinner: Marine Debris and its Effects on Seabirds --Guest Post--

Plastic Dinner. Photo by Alex Bond.

Imagine carrying around several kilos (or
pounds) of plastic in your stomach, unable to rid yourself of it, and gradually
adding pieces day by day. This is
what many marine animals go through every day. Millions of pieces of plastic enter the world’s oceans each
day, and once it’s there, it doesn’t go away. Instead, it breaks into smaller and smaller pieces. But every piece of plastic ever produced
by humanity exists in some form or another today. And it will for years to
come.

Seabirds mistake floating plastic for food
(pieces of squid, fish eggs, small invertebrates), and ingest them everywhere
from Tristan da Cunha (the most remote island in the world; in the South
Atlantic Ocean) to the Canadian Arctic. Aside from the obvious physical damage from eating (often large) bits of
plastic, plastic floating in the ocean acts like a sponge to sop up hydrophobic
contaminants (those that don’t like water), like PCBs, DDT, and newer chemicals
like polybrominated diphenyl ethers (PBDEs, used as flame retardants). Once in a bird’s stomach (which is warm
and acidic), the outer layers of the plastic, with the tag-along contaminants,
enters the bird’s body.

Thick-billed (L) and Common Murre (R). Photo by Alex Bond.

In Canada, we know very little about which
species ingest plastic, in what quantities, and the influences of this
behaviour. About 2 years ago,
while chatting with some colleagues in Newfoundland, someone mentioned that
there were data sheets from about 1200 Thick-billed Murres (Uria lomvia) used in a study of diet in
the mid-1980s. Murres (both
Thick-billed, and Common (Uria aalge))
are harvested legally in Newfoundland and Labrador each winter (and are rather
delicious!). Back in the 1980s,
scientists worked with harvesters to examine the contents of murres’ stomachs,
and better understand what murres ate outside the breeding season; they made note of any plastics they found.

In the mid-1990s, some other folks did the
same thing, using about 400 murres to look at what changes the 1992 groundfish
moratorium had on murres’ ecology and diet. Thankfully, they also recorded ingested
plastic.

We pulled together these original
datasheets, and 15-year-old spreadsheets, along with our own sampling of about
50 birds in 2011-12 to try and understand if murres’ rate of plastic ingestion
had changed over time, and whether there were differences between the two
species, and between adult and first-winter birds. The bottom line is that about 7-8% of
murres, regardless of species or age, contain at least some plastic. And, this has been the case since
the 1980s. This is surprising for
two reasons:

First, murres dive for their food. Deep. Up
to 180 m deep. We don’t expect to
find a lot of plastic there, since most of it is concentrated at the surface.

Second, plastic production has increased
over time, and so we would expect an increase in the plastics in murres, but
that wasn’t the case. In general,
there was more plastic ingested in the 1980s, and less in the 1990s (our
2011-12 sample was in the middle).

What also makes this study important is
that it’s one of the few studies that have looked at changes in plastic
ingestion over time (in Canada, or elsewhere) with relatively large sample
sizes (>40). It’s still not
perfect, since samples came from all across Newfoundland, so there could be
subtle spatial differences that we couldn’t figure out, but it’s a heck of a
lot better than what we knew before (which was, essentially, nothing).

So while murres aren’t affected by plastics
enough to cause problems (either to individual birds, or murre populations),
other species aren’t so lucky.

In Australia, about 95% of Flesh-footed
Shearwater (Puffinus carneipes)
chicks have plastic numbering tens to hundreds of pieces. In many cases, it’s a likely cause of
death for many chicks on Lord Howe Island in the Tasman Sea.

55.5 g of plastic/person on Qantas flight from Sydney to Lord Howe Island. This adds up to about 2.1 metric tons/year. Photo by Alex Bond.

Working on applied conservation can be
challenging – not just because the work is hard, or the field sites remote, but
because it’s easy to feel a sense of despair. Humanity is not going to stop producing plastic. And even if the last bit of plastic ever were made today, its legacy would
be around for hundreds (and maybe thousands) of years. But I (and you) can do something. We can use science to understand the
effects of plastics on marine life, and to bring about better pollution
control.

But one thing everyone can do is cut down
on the new plastic we use - in everything from face wash with “microbeads”
(plastic that goes down the drain) to packaging, and plastic bags to toys.

Photo by Donald Pirie-Hay.

Dr. Alex Bond has been studying the effects of pollution, climate change, and fisheries on marine birds since 2005, and has worked in Newfoundland, the Aleutian Islands of Alaska, and Australia. He is currently a Visiting Research Fellow at Environment Canada in Saskatoon, Saskatchewan, Canada. You can follow him on Twitter and visit his blog. The views in this post do not necessarily reflect those of his employer.